Etoile has been one of my favorites from Sanrio but for some reason, I kinda didn't like when I visited a dream and started talking to her. She's probably too pastel or colorful for my taste. So I would pick Stella. I like her color a lot and the simplicity of her design.
I do think Etoile would fit in well with Marshal and Diana and she's actually the only sheep I like. I wasn't keen at first but after I kept scanning in her RV her appearance has grown on me. Find her much prettier than other sheep so she gets my vote
I have Stella in my second GCN town and Vesta is currently in my New Leaf town (might plot reset to get Mitzi though). They're both good villagers IMO (Stella's design in Animal Crossing/Doubutsu no Mori+, Doubutsu no Mori e+ and Animal Crossing: New Leaf looks MUCH better than here original design in Doubutsu no Mori N64).